l lewis



H. F. LEWlS.

PROCESS OF LAYING SHEET GLASS.

APPLICATION FILED N0v.3.1915.'

l. A M mmy" Emma Aug. 15, 1915.

iNVENTO H WA TOWNEV HARRY J. LEWIS, 01? FORD CITY, PENNSYLVANIA,ASSIGNOB T0 PITTSBURGH PLATE GLASS (WMPANY, 01? PITTSBURGH,PEINTNSYLVANIA, A CORPORATION OF PENNSYL- .VMIA.

PROCEEZS Oil LAYING SHEET-GLASS. I

( Application filed November 3, 1915. serial No. 59,334..

To all whom may concern:

Be it known that l, HARRY F. Lewis, a' citizen of the United States,residing .at

Ford City, Armstrong county, and State of 6 Pennsylvania, have inventeda certain new and useful Process of Laying Sheet-Glass, of wl ich thefollowing is a specification.

The invention relates to a process for laying sheet glass upon thegrinding and polish- 10 ing tables and securing it thereto by means ofplaster of Paris or similar material capable of being hydrated andsetting rapidly. It has for its primary objects; the provision of animproved process having the following advantages as compared with theprocess now in use; (1). a saving of time in the application of theplaster, (2) a saving in the amount of plaster, (3) increased strengthin the holding layer of plaster, (4) a saving in 0 the labor required inapplying the plaster, and a more uniform distribution of the plaster.The process is illustrated in the ac-. companying drawings whereinFigure 1 is'a side elevation of the apparatus employed with certainparts in section; Fig. 2 is a perspective view showing the up plicationof the hydrated plaster of Paris to the grinding table to which theglass is to be applied; and Fig. 5 is a perspe tive new showing theapplied to the table.

Plate glass is secured upon the grinding and polishing tables by meansofplaster of Paris. lleretoforc it has been custon'iary to mix the plasterof Paris with water and ap: ply it by means of buckets to the surface ofthe table, the plaster being spread as uniformly as possible over thesurfaceof the table and the glass then pressed into position in thelayer of plaster. Thcrc are certain well known disadvantages incident tothis process of laying glass. Considerable time is consui'ned in gettingthe plaster on the table and properly sn'ioothed before the glass isapplied, and in this period a certain setis imparted to the plaster andas a result the bond between the glass and the table is not as secure ifthe glass were applied before the initial set of the plaster. it is alsodillicult to spread the plaster in a layer of m uniform thickness, andas a result it often happens that parts of the surface of tl'ie glassare higher than otl'u-irs. so that in the grinding operation the sheetis unduly thin at some parts. The high parts of'the glass M sheets areusually the central portioi'is, as

there is more resistance of the plaster against lateral movement atthese points when pressure is applied to the surface of the lass topress it into position and squeeze out the surplus plaster from betweenthe table and the 00 glass. As the application is not uniform and thelayer must be of sutlicient thickness at all points, an excess ofplaster must be used, and this excess is lost or Wasted when the sheet15 pressed into position. There is also an additional loss of plasterincident to the mixing in the buckets and to the handling. It is theptrrpose of my invention to provide a proeesswvhich is free from theforcgo ng objections, and to that end I provide a means whereby thepowdered laster of Paris is projected in a stream, and hydrated duringits passage through the air so that the mixed plaster of Paris and Wateris sprayed upon the table to form a layer of an desired thickness. I I

I The apparatus which I ')refcrably employ in carrying out this processis illustrated in Fig. 1, wherein 1 is a container for the powderedplaster of Paris 3 and 4- are pipes su 'iplied with air under pressurefrom the pipe 5 leading from a source of com 'iressml air 3; .7 is a.flexible tube leading to the nozzle H; and 9 is a flexible water supplypip'e leading to the casing 10.

The lower end of the pipe 3 is guided in the block 11 secured to thepipe 4, and the pipe 4 is adjustal'ilc back and forth in the casing bymeans of the screw 12 so that the space between the block 11 and theinclined bottom of the casing 1 can be varied to adjust the feed of theplaster .of Paris. The connection 13 is flexible to permit thismovement, and the pipe 4 is perforated.throughout its length to permitthe air to pass tlirough the plaster of Paris and feed it forward. Avalve 14 in the air pipe gov erned by the connections 15. permits of theregulation of the air supply. It will be seen thatthisarrangementprovides for the 'n-ojcr.:tion under pressure of a mixture of plaster ofParis and air through the pipe 7 and the nozzle 8. The nozzle 8 isprovided with 'aseries of forwardly projecting openings 16 by means ofwhich water is admitted .to the nozzle from the casing 10.

in operation, the nozzle is used to spray .the mixed plaster and waterupon the surface of the table 17 asdndicatrd' in Fig, 2, the method ofapplication correspomling to that in painting with an air brush. Thematerial. is sprayed over the area to wh ch the sheet of glass is to beapplied until a layer of the desired thickness is provided,

' plied ,little excess plaster to after which the sheet of and pressedinto osition. In case another sheet is to be app ied to the same table,the process is repeated, the sheets 18 and 19 as applied to the tablebeing illustrated in Fig. 3.-

I have found that by the use of this method, the plaster of Paris can beapin,a fraction of the time required by the old process, and that it canhe applied in glass is applied a, layer of uniform thickness, thussecuring a, saving in time and in plaster. Since-the plaster can beapplied uniformly there is be squeezed out and the upper surface of theglass is more level than was the case with the old process. I also findthat the bond between the plaster and the glass ismuch stronger thanwith the old process and this, I believe, is due to the fact that theperiod of application ofthe glass is much less than with the, oldprocess, so that there is a timehetween the. imixture of the plaster andwater and the smaller less of strength due to the initial set occurrmgbetore the glass is in position. The mixing of the plaster and water isalso more thorough since there is no opportunity for the materials tobecome unmixed as is the case where the mix ng is done in buckets, andas a result the mixture is more uniform with my process and the strengthof the plaster is greater. A further saving of time with the new processoccurs in the 0peration of pressing the glass down into the plaster ofParis in a stream, hydrating the said stream as it moves forward,directing' the said stream upon the table to form a bed of uniformthickness, and then apply ing a glass sheet upon the said hcd.

HARRY F. LEWIS.

